Controllable pitch propeller



Nov. 22, 1949 M. M. SENSENICH ETAL 2,438,686

CONTROLLABLE PITCH PROPELLER Filed May 29, 1945 v ,4 Sheets-Sheet 1 v lvuclnfoz 1949 M. M. SENSENICH ETAL 2,483,686

CONTHOLLABLE PI TCH PROPELLER Fil ed May 29, 1945 4 Sheets-Sheet 2mic/"(00.3

7 s h' p MOI/M4415 Nov. 22, 1949 I M.YM. SENSENICH ETAL 2,438,636

CONTROLLABLE PITCH PROPELLER Filed May 29, 1945 I 4 Sheets-Sheet sfinucutou' Nov.. 2 1949 M. M. SENSENICH ETAL 2,488,686

CONTROLLABLE PITCH PROPELLER 4 Sheets-Sheet 4 Filed May- 29, 1945 Sam; 3

Patented Nov. 2, 1949 I UNITED STATES PATENT OFFICE- 2,488,686 ICONTROILABLE PITCH PBOPELLEB Martin M. Senscnich, Lancaster, and HaroldR.

Uhrich, Lititz, Pa., assignors, by mcsnc assignments, to ScnsenichCorporation, Lancaster County, Pa., a corporation of PennsylvaniaApplication May 29, 1945, Serial No. 596,442

This invention relates to controllable propellers or propellers in whichthe pitch of the propeller blades may be adjusted and controlled duringflight or during rotation of the propeller, such adjustment in theembodiment illustrated 13 Claims. (Cl. 170-16032) being from a fixedhigh pitch position to a fixed low pitch position, or vice versa.

The propeller of the present invention is of the so-called hydrauliccontrol type and its blades are to be moved or rotated about their axesfrom one of their operative positions to the other by a suitable fluid,most usually oil under pressure, which may be oil diverted from theengine lubricating system under pressure, said blades being moved orrotated in the reverse direction by the action of weights secured insuitable manner to the blades, usually to their stems or roots, or bythe centrifugal action of the mass of the blades and aerodynamic forcesacting to move the blades toward their low pitch or neutral positionswhen free of the hydraulic control. In order to supply the operativefluid, such as oil from the engine lubricating system, to the propellerhub to operate the actuating parts thereof, the engine shaft S is formedwith an' axial passage or bore in accordance with known construction,which bore 0 or passage is in communication with the interior of the hubtube 30, and suitable tubing or ducts may be provided in conjunctionwith a suitable control plug or cock preferably disposed on or adjacentto the panel or instrument board in the plane cabin whereby when theplug or cock is turned to one position the oil under pressure will flowfrom a pump or pressure tank or body of oil under suitable pressure intoand through the central longitudinal or axial bore 0 of the shaft S andfrom there through the tube 30, and

whereby when the plug or cock is turned to another position it closescommunication between the bore 0 and the oil supply and openscommunication between the bore 0 and the engine crank case or a sump sothat the oil may flow or escape from the hub when the blades move backto their initial positions under the action of the weights or by theaction of centrifugal force and aerodynamic forces when they are freedof the influence or thrust of the hydraulic system or fluid pressure, inaccordance with such hydraulic or oil pressure systems as shown in anyone of the patents as follows: German Patent 301,635, Lorenzen, April 7,1920; 1,565,100, Nutt, Dec. 5, 1925; or 2,032,255, Caldwell, Feb. 25,1936, or my invention may be embodied in that type of propeller whichhas its own independent supply or fluid together with means forsupplying some of such fluid to the hub with such force or pressure aswill suflice to properly actuate the parts and result in moving theblades about their axes from one pitch position to 'another togetherwith means permitting the fluid to escape from 2 I the operativecylinder of the hub, and preferably back to the main body of fluid, whenthe pressure is released and the blades move back to their initial pitchpositions as above mentioned.

Since the source of supply of the fluid under pressure and the means ofcontrol are old and well known and form no part of this invention, thereis believed to be no need for further description, or for illustrationthereof and therefore the remainder of this specification, and thedrawings, are confined to the propeller per se and the operative partsthereof.

The primary objects of the present invention are: to provide a propellerof the type mentioned in which all parts operative to adjust the pitchsetting, the extent of the pitch movement of the blades, and the entirerange of pitch movement are enclosed and yet which is quickly adjustablein the assembled operative condition of the propeller without need toremove a blade or section of the hub, it being sumcient to remove simplyan access opening plug or closure and to release or partially screw outa locking means or bolt or pin; to simplify the construction andassembly and increase the ease of accessibility to the parts of suchpropellers and their application to the drive shaft of the airplane orvehicle: to provide for the adjustment of the initial pitch of thepropeller blades to suit the characteristics of any given enginedeveloping maximum power and speed within the eneral en ine power andspeed range for which a given size of propeller is designed so that asingle standard model propeller may be produced in large quantities andsecured to the shaft of, and used with, any given engine of a largenumber of different types and makes of engines often having manydifferent characteristics as to their speeds of 'r'otation of theirpower shafts in relation to their most emcient development of power andby a suitable and simple adjustment of the propeller obtain the greatestdegree of efliciency of operation from said en ine; to providesimple'and efiicient means for adjusting the range of pitch movement asa whole; to provide simple and eflicient means for adjusting the extentof the range of angular adjustment between the high and low pitchpositions of the propeller blades to best suit the characteristics of agiven engine; and to provide simple and positive means for securing theparts in any given adjusted position.

In the accompanying drawings:

Figure 1 represents a view partly in side elevation and partly insection of the hub and root portions of the blades of a dual bladepropeller tion of the engine shaft S to which it is bolted or on whichit is otherwise suitably mounted being indicated by light dot anddashlines and having its boss B snugly fitted in the rear end amass ofthe bore of'the hub sectioned to show the oil bore or passagerlgure2,asectionalviewon-theline22ofrig.l.lookinginthedirectionofthearrowsandwiththeouterportionsofthebladeroots shown in side'elevatlon andbroken away;

l'igure3,asectionalview ontheline3-3of Hg. 1, looking in the directionof the arrows;

Figure 4, a fragmentary sectional view on the line 4-4 of Fig. 1,looking in the direction of the arrows;

l'igure5,atopplanviewoftheadlustableposition pitch adjusting oractuating traveler, spider or cross-head 2|;

I'igure 6, a front elevation thereof; Figure I, a side elevationthereof;

Figure 8, a top planviewof the addusting nut 21;

Figure 9,aviewpartlyinsectionandpartly in elevation of said nut 21;

rigurelmatopplanviewofoneoftheblocks It; and

Figure 11, a detail view showing the manner of locking the bladeretaining collars or nuts 8 against turning movement in the bladesockets of the hub.

both of these features facilitating greatly the ease and rapidity ofservicing and reconditioning or repairing, and the original assembly, ofthe propellers and both being considered important featm'es of ourinvention.

Referring now in detail to the drawings, 8deslgnatestheengineshafthavingaflangel? to which is bolted the flange 4of the propeller 'hubandabossBflttingintherearendofthe The drawingsillustrate a two blade or-dual I having three or more blades or only oneblade,

in any such case the hub of course to be modified correspondingly asalso the spider or cross-head 2| to receive and cooperate with all ofthe blades of a given propeller of a given type.

The propeller of our invention may be said to be comprised of three maingroups of elements, as follows: the blades I with their roots, ferules,end caps, split lock rings, bearings, races, retaining collars or nuts,locking means for the latter, all in general of conventionalconstruction and design, their pitch bosses or pins and their weightswhere the latter are employed; the hub per se; and the hydraulic orfluid pressure control mechanism. In turn, such hydraulic mechanism maybe said to be comprised of two main sub-groups of elements, the samebeing a composite sleeve and cylinder or chamber, with closure plate orcap unit and a piston and diaphragm with piston rod or thrust tube andoil or bydraulic fluid supply duct or communication duct unithereinafter referred to as the piston unit or assembly or assemblage.

The cross-head, or spider 2| adjustable axially of the sleeve portion 20of the composite sleeve and cylinder unit serves to operatively connectthe hydraulic mechanism to the blades to adjust the pitch of the latter,and the nut 21 engaging the exterior screw-threads of sleeve portion 2|]cooperates with an abutment face or portion of the hub per se to either,together with cross-head or spider 2|, adjust the position as a whole ofthe range of the pitch adjustment, or to adjust the extent of the rangeof pitch movement.

The hydraulic or fluid pressure control mechanism is easily and quicklyremovable as a unit and replaceable by a similar identic constructionunit, all without need for demounting or disassembling any otherelements or parts of the propeller, and the piston unit or assemblage bythe simple removal of the cylinder head or cover or plate ll isremovable and reinsertible or replaceable by a similar duplicate pistonassemblage without need for demounting or disassembling any otherelements or parts of the propeller,

here of the hub and being hollow or formed with an oil or hydraulicfluid duct or bore 0.

I tea the cylindrical, or preferably cylindrical body of the hubhavingits end portions internally screw-threaded to receive the externallythreaded retaining rings, collars or nuts I and formed with internalannular flanges 3 respectively spaced from the respectively internallyscrew-threaded portions sufliciently to accommodate between the innerfaces of the respective retaining rings, collars or nuts I and the outerfaces of the respective flanges 8 the respective blade root mountingassemblages.

The body I is formed with a central bore or opening extending at rightangles to the axis ofsaidbody I andacenteringsupportorguide bush orbearing 2 is brazed, welded or otherwise suitably secured or formed inthe front wall of said opening in axial alignment with a similar bush orbearing 3 similarly secured or formed in the rear wall of said openingand said bushes or bearings 2 and 3 may be. vided with suitable bearinglinings 2' and 3'\}pectively.as illustrated, in any suitabb u r, and thepropeller mounting flange l is secui @to the rear end of the bush orbearing 3 and to the adjacent portions of the body I at all points aboutthe bush or bearing 3 by welding or brazing or in any other suitablemanner, and preferably said flange l is formed with bolt holes toreceive cooperating bolts II also received by similar bolt holes in theflange of the engine shaft 8, nuts being turned on said bolts to securethe propeller to said shaft.

The bush 3 preferably is formed with a radial inner shoulder 5, thatportion of its inner face on the front side of said shoulder being ofsmaller diameter than the front bearing 2 to snugly receive, support andguide the reduced rear end of the sleeve III and being of largerdiameter rearwardly of said shoulder 5 to receive and support in propercentered position the abutment plate or disc 33, which is held in placeby the pressure of the engine shaft boss B and a suitable fluid sealinggasket 35 of any suitable preferably compressible material interposedbetween the annular end face of said boss B and the radially outerportion of the opposed face of disc 33.

There will be, of course, a blade 1 for each blade socket of the huh I,there being two sockets and hence two blades in the embodimentillustrated, and such blades I will be mounted and retained in theirsockets by any suitable conventional mount-' ing and bearing means. Inthe embodiment illustrated such conventional means employs for eachblade a ferule I having an annular groove adjacent its inner end, an endplate or caps Ia secured to the extreme end of the blade root and makinga snug flt inside of the flange 8 of the blade socket with anupperflange resting on the outer face of said flange 3, a split lockingring II composed of two semi-circular metal pieces retained in positionin said groove by the retaining element or ring I I with its innerportion or flange extending axially of the blade to flush with the innerfaces of the members ofthe locking ring III and engagas the innerroller; race, an outer-roller race G'aa roller bearing assembly 6interposed between the race 6' and retaining ring Ill, an externally.screw-threaded retaining ring, collar or nut 9 engaging the internalthreads in the;.outer end portion of the corresponding blade socket ofthe hubi and pressing against the outer face of the outer race 6', aring form antifriction. micarta lining to for thesocket, and,preferably, some suitable means for locking the collar or nut 9 againstturning, such as a band 9' having a portion fitting in an externalannular groove of the corresponding blade socket and having a lockfinger or tongue 9a fitting into anyone of a series of recesses ornotches in theaxially outer face of the collar or nut 9.

A pitch adjusting lug or stud 25 is secured to the end of the root ofeach blade to extend axially of the blade at a point remote from theaxis of the blade, preferably as remote therefrom as practical to obtainthe benefit of as much leverage as possible, and said lug or stud 25 maybe either formed as an integral part of the cap Ia, or it may be formedseparately with a stem pressed or driven into a corresponding hole ordrilled bore in said cap with a tight fit and thereafter welded orbrazed to said cap as illustrated.

Weights may be secured to the respective blades 1 in such angularpositions as to tend to turn said blades to and maintain them in theirhigh pitch position during the rotation of the,

propeller unless and until counteracted by the positive action of thehydraulic mechanism acting to forcibly turn them to, and hold them in,their low pitch positions while the oil or other fluid is supplied underpressure, or maintained under pressure, to said hydraulic mechanism. Tothis end each weight M is connected to a band l2 to encircle the stem orferule of a blade I and is provided with a nut and bolt l3 or othersuitable means for drawing said band into tight binding and lockingengagement with said stem or ferule 1a, preferably; the ferule, to holdthe said weight M in any selected angular position of ad justmentthereon against movement relative thereto. Said weights may be of anysuitable construction and may be of such construction that theireffective weight can be varied as desired by employing anyone of aseries of supplemental weights, this being old and well known in theart.

The sleeve 20 is. preferably integral with the enlarged cylindrical cupor cylinder 31 at its forward or front end, and is formed withthreeexternal cylindrical portions, being an extreme rear end reduceddiameter bearing portion l6 making a snug sliding fit in the rear bushor bearing 3 for reciprocatory movement therein, an intermediateexternally screw-threaded portion l1, and a large diameter bearingportion l8 making a snug sliding fit in the front bush or bearing 2 forreciprocatory movement therein, and is formed in said front portion |8with a plurality of equi-distantly spaced locking slots l9 arranged in acircular series and extending entirelythrough the wall of the sleeve 20,at least it is preferred thatthey be arranged ina circular seriesandthat they extend entirely. through the wallofthe sleeve 20, thoughneither of these attributes is essential so long as they be so formedand so arranged as to meet the needs for, locking the sleeve-20 againstrotary movement while permitting it to have such extent .ofreciprocatory movement in any posi-' tion'of adjustment of the parts aswill permit it to function asrequired; I

The threads ofthe externally-threaded portion ll engage the threads'ofthe internally screwthreaded pitch adjusting" or actuating traveler,spider or cross-head 2| to, by the rotation of the sleeve 20, adjust theformer axially of the sleeve 20 to any position ofadjustment for theinitial position of the blades, or tosuch initial angular adjustment ofthe blades as may be called for by the characteristics of a givenengine, the range of pitch movement of the blades starting from suchinitial position of angular adjustment.

The adjusting nut 21 for, in association with said spider or cross-head2|, adjusting the range of pitch movement as a whole without varying theextent or degree or length of such pitch movement, or of varying theextent of such pitch movement independent of the spider or cross-head2|, is mounted on the sleeve 20 in advance of the spider or cross-head2| with its internal screwthreads in engagement with the screw-threadsof the screw-threaded external portion ll of said sleeve 20, and byengagement with, or abutment against, the rear end or abutment face 21of the bush or hearing 2, serves or functions to limit the forwardreciprocatory sliding movement of the sleeve 20.

While the screw-threaded portion I1 is of greater external diameter thanthe rear end bearing portion It to permit the adjusting nut 21 andspider or cross-head 2| to be slipped over the portion It and engagewith the threads of portion I! to be thereby moved into and held inadjusted position axially of the sleeve 20, the said screwthreadedportion I1 is preferably of slightly less diameter, at its extremegreatest external diameter, than the external diameter of the forwardbearing portion l8 to the end that the screwthreaded portion l1 may beeasily inserted through the bush or hearing 2 and the forward bearingportion l8 makes a snug free sliding fit in said bush or bearing 2 forreciprocatory movement therein.

A lock stud or pin l5 having a screw-threaded portion engaging thethreads of an internally screw-threaded bore or hole through the wall ofbush or bearing 2 and a preferably smooth uniform diameter tip or toe tofit in anyone of said slots ll] of said series of locking slotsfunctions to lock said sleeve against any turning movement or anysubstantial turning or rotary or partial rotary movement, so that oncethe initial position of angular adjustment of the blades 1 has been madeby causing the'movement of the spider or cross-head 2| axial of thesleeve 2n by turning the sleeve 20 through the spider or cross-head 2|,the lock stud or pin l5 having'first been removed to permitsuch turningof the sleeve 20, the parts, may be locked in such adjusted relationshipby replacing the lock stud or pin l5 and turning it home in its bore ortoe or tip portion in one of the slots l9. Preferably the diameter ofthetip or toe of the pin IE will be just slightly less than the width ofanyone of the uniform width slots l9 so as to be snug- 1y receivedbetween the opposing axial walls thereof.

While, when the locking pin or stud I5 is removed, the sleeve 20 may beturned, and the adjusting nut 21 will turn with it unless held againsthole with its smooth 23 suitably secured to the interior face of orintegral with the hub body I in such positions respectively as to beslidably engaged by the inner faces of the extreme end portions of therespective arms 22 of the spider or cross-head2 l, whereby said stops orlugs 23 will support, and permit axial movement of, the arms 22 of saidspider or cross-head 2| while preventing rotary movement of the saidspider or cross-head 2|.

The outer faces of the arms 22, that is the faces presented toward therespective caps or cap plates la of the blades 1 are respectively formedwith guide-ways 24 to slidably receive the eccentric or slightlyoff-center bored compensating guide blocks 26, which respectively snuglyreceive in their respective bores the pitch adjusting lugs or studs 25respectively extending or projecting from the respective caps in of therespective blades 1, which studs or lugs 25 will be arrangedrespectively at such angular positions with relation to the axes oftheir respective blades as to maintain the proper relationship betweenthe blades of the propeller in all angular positions of the respectiveblades throughout the range of pitch movement thereof including theirpositions of high and low pitch.

From the foregoing it follows that any movement of the spider orcross-head 2| in a direction axially of the sleeve 20, whether with thesleeve 20 or relative to the sleeve 20 will result in some pitchmovement of the blades 1 about their respective axes and in equal degreeand proper relationship, and similarly that any axial movement of thesleeve 20 will result in movement of the spider or cross-head 2| in adirection axial of the sleeve 20.

The adjusting nut 21 will preferably be slotted perpendicularly to itsaxis and will have one portion on one side of the slot mashed ordeformed or pressed toward the other such portion, and this may berepeated at a diametrically opposite portion of the nut, so as todistort the thread of the nut, which is of a suitable springy orresilient material, such construction being for the purpose of holdingthe nut 21 on the sleeve in any position axially thereof to which it maybe adjusted while permitting the nut to be held against turning whilethe sleeve 20 is turned to thereby cause axial movement of the nut 21 onthe sleeve 20 to a new axial position of adjustment thereon. The nut 21may be held against turning by any suitable tool or instrument insertedthrough the access opening of bore 28 and for this purpose the outerperiphery of the nut 21 is formed with a plurality of preferablyequi-distantly spaced notches. While the above construction of the nut21 is preferred, it may be formed in any manner or shape suitable to thepurpose and such as ,will serve the functions mentioned.

By holding the nut 21 against turning and removing the locking pin I5,the spider or crosshead 2| and the nut 21 may be simultaneously adjustedaxially of the sleeve 20 to adjust the range of pitch adjustment as awhole without varying the extent of such range, or the extent of therange of such pitch movement may be varied by leaving the pin IS inplace to lock the sleeve 20 against turning and simply turning the nut21 on the sleeve 20 by means of a suitable tool operated through theaccess opening 28.

The compensating block 26 is square so that it may be inserted in theslot or guideway 24 of its corresponding arm 22 in any one of fourpositions to obtain a fine adjustment of the initial pitch position orto compensate for wear of the parts.

A thrust or piston rod 33 having a rear end nipple snugly slidablyremovably fitting in and preferably through the central opening of theabutment plate or disc 33 extends lengthwise through the sleeve 23 andnearly to the cylinder head or front or cover plate 40, having anexternally screw-threaded nipple extending through a dished form piston34 and a flexible diaphragm 38 of any suitable material, such forinstance as molded neoprene, a nut 35 turning on the extreme front endportion of said threaded front end nipple extending forward beyond saiddiaphragm to tightly clamp said piston 34 and diaphragm 38 between saidnut 36 and an annular flange or shoulder 32 integral with or rigidlysecured to the forward end portion of said thrust or piston rod 30. Therear end portion of the thrust or piston rod 30 is formed with anannular flange or shoulder 3| integral with said thrust or piston rod 30or rigidly secured thereto and exerts a thrust against the abutmentplate or disc 33.

The thrust or piston rod 30 is held in proper centered relation to thesleeve 20 and cylinder 31 by the abutment plate or disc 33 at its rearend and the piston at its front end making a snug sliding fit in theinternal cylindrical space of the cylinder 31.

The diaphragm 33 is preferably formed with a peripheral bead presentedforwardly toward the removable cylinder head or cover plate 40, which isprovided with a preferably integral internally screw-threaded rearwardlypresented flange engaging an externally screw-threaded portion of theforward end of the cylinder 31 and formed in its rear face with a groovein line with the front face of edge of the cylinder 31 to receive theperipheral head of said diaphragm 38 and to tightly clamp the peripheraledge portion of the said diaphragm between the cylinder 31 and thecylinder head or cover plate III to thus seal the joint between thecylinder 31 and the cylinder head or cover plate III at all pointsagainst the escape of fluid, the joint between the piston 34 and thediaphragm and thrust or piston rod 30 being similarly sealed at allpoints by the nut 36 clamping the diaphragm 38 and piston tightlyagainst the flange 32, such construction resulting in the provision of afluid tight chamber 39 in the cylinder 31 and defined by the rear faceof the cylinder head or cover plate 40 and the diaphragm and varying insize according to r the variations in position of the cylinder 31 andsleeve 2|! according to the oil pressure or absence thereof in thechamber 33.

After the cylinder head or cover plate 40 has been turned up tight itmay be locked against unscrewing by any suitable means, for instance bytie wires passing through any number of a series of small holes in theradially outer rear portion of the rearwardly presented flange of thecylinder head II and corresponding holes in any of a plurality of websor ribsformed in the outer peripheral wall of the cylinder 31 as shown.

Similarly, the nut 36 is locked to the end of the thrust or piston rodin any suitable manner, as by cotter pins passing through holes drilledthrough said nut 35 perpendicularly to its axis and fitting in slotsextending axially of the screwthreaded front end nipple of said thrustor piston rod 30.

The said thrust 0r piston rod 30 is hollow or tubular in form with bothends open to constitute an oil duct with its rear end in communicationwith the oil duct or bore 0 of the engine shaft S and with its front endin communication with gages the abutment face 21 of the front bush orbearing 2 and moving the blades 1 about their axes from high pitch tolow pitch for take off and climbing. When the supply of oil underpressure is shut oif and the oil return or drain is opened,

- the weights will act, as the propeller rotates to turn the bladesabout their axes toward high pitch and as said blades thus turn theirpitch pins will shove the spider or cross-head 2!, together with thesleeve 2", cylinder 31 and cylinder head or cover plate 40 rearward,thus expelling the oil in the chamber 39 through the thrust or pistonrod 30, oil duct or bore B and suitable drain tubing or piping, notshown, to

the engine crank-case or a sump, not shown, from which' it willeventually be returned to the oil pump or source of oil under pressure,or, in the case of a self-contained oil pressure system within thepropeller as an operative unit, from the chamber 39 through the thrustor piston rod to the rear of the abutment plate or disc 33 and fromthere back to the fluid system of the hydraulic mechanism'to be held ina suitable reservoir or other storage means to be again used as theoccasion may require.

While I prefer to supplement the piston 34 by the diaphragm 38 toprovide a more eflicient liquid sealing off of the expansion chamber ofthe cyl-- I inder, the use of such a diaphragm is not essential and itmay be dispensed with.

Also, while I have shown and described a pro peller in which the bladesare moved to low pitch by the hydraulic mechanism, that is, by theadmission of oil'under pressure to the chamber 39, and are moved back tohigh pitch position by the weights H, the arrangement might equally wellbe exactly the reverse, the hydraulic mechanism in such case moving theblades to high pitch and holding them in high pitch during straight awayflying and the weights H tending to move the blades to low pitch, inthis supplementing the normal inherent action of the bladesmasses, orthe weights in such case might be entirely eliminated and relianceplaced altogether on the centrifugal action of the blade masses toreturn the blades to low pitch position.

From the foregoing description it will be seen that when the cylinderhead or cover plate 40 has been removed the piston assembly can beeasily and quickly removed as a unit, simply by pulling forward on thefront nipple of the thrust or piston rod 30 or on the diaphragm 38; andalso that the hydraulic system may be removed as a unit simply byremoving the lock pin I5 and then turning the sleeve 20 to screw itforward until it is free of the spider or cross-head 2| and orinstrument to either hold the nut 2! stationary or to manipulate it toturn it to move it in either axial direction with relation to the sleeve20, and said opening will preferably be closed by bearing 2 functions tolimit the rearward reciprocatory movement of the sleeve 20 in thebearings 2 and 3 of the hub I, preventing such rearward movement of thesleeve 20 beyond its position shown in Figure 1.

We claim:

1. A controllable pitch propeller comprising a hub, propeller bladesmounted in said hub, and pitch pins respectively extending from saidblades, in combination with a sleeve slidably mounted for reciprocationin said hub and having a medial externally screw-threaded portion,hydraulic mechanism for forcing said sleeve in one direction axiallythereof, releasable means for locking said sleeve against rotarymovement relative to said hub while permitting its axial movementtherein, a spider having screw-thread engagement with the screw-threadedportion of said sleeve and carrying means engaging said pitch pins tocause said blades, spider and sleeve to' move together in either axialdirection of,

formed with a closable access opening to permit adjustment of said nutaxially of the sleeve in the assembled operative condition of thepropeller either independently of, or simultaneously and to the sameextent with, said spider, said spider being adjustable to differentpositions axially of the sleeve independently of said nut.

2. A controllable pitch propeller comprising a hub, propeller bladesmounted in said hub, and pitch pins respectively extending from saidblades, in combination with a sleeve slidably mounted for reciprocationin said hub and having an externally screw-threaded portion, hydraulicmechanism for forcing said sleeve in one direction axially thereof,releasable means for locking said sleeve against rotary movementrelative to said hub while permitting its axial movement therein, aspider having screw-thread engagement with the screw-threaded portion ofsaid sleeve and carrying means engaging said pitch pins to* cause saidblades, spider and sleeve to move together in either axial direction ofmovement of said sleeve, and an adjustable pitch movement limiting nuthaving screw-thread engagement with the screw-threaded portion of saidsleeve and normally turning therewith and limiting the extent of thepower thrust movement of said sleeve by engaging a relatively fixed partcarried by said hub, said spider being adjustable to different positionsaxially of the sleeve independently of said nut by rotation of saidsleeve relative to said hub. I

3. A controllable pitch propeller comprising a hub, propeller bladesmounted in said hub, and .pitch pins respectively extending from saidblades, in combination with a sleeve slidably mounted for reciprocationin said hub and having an externally screw-threaded portion, hydraulicmechanism for forcing said sleeve in one direction axially thereof,releasable means for holding said sleeve against rotary movementrelasaasse 1i ative to said hub while permitting its anal move-4 menttherein, a spider having screw-thread engagement with said sleeve andcarrying means engaging said pitch pins to cause said blades, spider andsleeve to move together in either axial direction movement of saidsleeve, and a nut having screw-thread engagement with said sleeve andnormally turning therewith and limiting the extent of the power thrustmovement of said sleeve by engaging a relatively fixed part carried bysaid hub, said nut being adjustable to different positions axially ofthe sleeve independently of said spider in the assembled operativecondition of the propeller.

4. A controllable pitch propeller comprising a hub, and propeller bladesmounted in said hub, in combination with a sleeve slidably mounted forreciprocation in said hub and having an externally screw-threadedportion, hydraulic mechanism for forcing said sleeve in one directionaxially thereof, releasable means for locking said sleeve against rotarymovement relative to said hub while permitting its axial movementtherein, a spider having screw-thread engagement with said sleeve, meansfor preventing substantial rotary movement of said spider relative tosaid hub and for so connecting said spider and blades that said blades,spider and sleeve move together in either axial direction movement ofsaid sleeve, and a nut having crew-thread engagement with said sleeveand normallyv turning therewith and limiting the extent of the powerthrust movement of said sleeve by engaging a relatively fixed partcarried by said hub, said spider and nut being adiustableto differentpositions axially oi the sleeve independently of each other.

5. A controllable pitch propeller comprising a hub, and propeller bladesmounted in said hub, in combination with an element slidably mounted forreciprocation in said hub and having an externally screw-threadedportion, hydraulic mechanism for forcing said element in one directionaxially thereof, releasable means for holding said element againstrotary movement relative to said hub while permitting its axial movementtherein, a spider having screw-thread engagement with said element,means for so connecting said spider and blades that said blades, spiderand element move together in either axial direction movement of saidelement, and a nut having screw-thread engagement with said element andnormally turning therewith and limiting the extent of the power thrustmovement of said element by engaging a relatively fixed part carried bysaid hub, said spider being adjustable to different positions axially ofsaid element independently of said nut, said nut being adjustable todifferent positions axially of said element independently of saidspider, and said spider and nut being simultaneously adjustable todifferent positions and to the same extent axially of said element byrotating said element with relation to both said spider and nut.

6. A controllable pitch propeller comprising a hub, propeller bladesmounted in said hub, a spider disposed in said hub for movement in thedirection of the axis thereof, said spider being internallyscrew-threaded, means for preventing rotary movement of said spiderrelative to said hub and for so connecting said spider and blades thatsaid blades will move about their axes simultaneously with, and inproportion to the extent of, an axial movement of said spider, and anabutment having a smooth bore extending axially of the hub and sealingoff at all other points a space to the rear of said abutment. incombination with hydraulic control means for forcing said spider axiallyof said hub in one direction and permitting its reverse axial movement,means for limiting the extent of the axial movement of said spider, andreleasable means for locking said hydraulic control means in the hub,said hydraulic control means comprising an externally screw-threadedsleeve fitting within and having screw-thread engagement with saidspider and being slidably mounted in said hub, a cylinder carried bysaid sleeve, a tube fitting within the bore of said abutment andexerting a thrust against the latter and removable from said bore by astraight forward movement and establishing communication between thespace behind said abutment and said cylinder, and means connected tosaid tube and disposed within said cylinder for causing the axiallyforward movement of said sleeve, said hydraulic control means beingremovable from, and replaceable in, said hub as a single unit and whileall other parts of the propeller remain in normal operative assembledcondition.

7. A controllable pitch propeller comprising a hub, propeller bladesmounted in said hub, a spider disposed in said hub for movement in thedirection of the axis thereof, said spider being internallyscrew-threaded, means for preventing rotary movement of said spiderrelative to said huband for so connecting said spider and blades thatsaid blades will move about their axes simultaneously with. and inproportion to the extent of, an axial'movement of said spider, and anabutment having a smooth bore extending axially of the hub and sealingoff at all other points a space to the rear of said abutment, incombination with hydraulic control means for forcing said spider axiallyof said hub in one direction and permitting its reverse axialmovement,.and releasable means for holding said hydraulic control meansin the hub, said hydraulic control means comprising an externallyscrewthreaded sleeve fitting within and havingscrewthread engagementwith said spider and being slidably mounted in said hub, a tube fittingwithin i the bore of said abutment and exerting a thrust against thelatter and removable from said bore by a straight forward movement andestablishing communication between the space behind said abutment andthe interior of said hydraulic control mechanism, said hydraulic controlmeans being removable from, and replaceable in, said hub as a singleunit, and while all other parts of the propeller remain in normaloperative assembled condition.

8. A controllable pitch propeller comprising a hub, propeller bladesmounted in said hub, a spider disposed in said hub for movement axiallythereof, saidspider being internally screwthreaded, means for preventingrotary movement of said spider relative to said hub and for soconnecting said spider and blades that said blades will move about theiraxes simultaneously with, I

' control means comprising an externally screwthreaded element fittingwithin and having screwthread engagement with said spider and being 3slidably mounted in said hub, a tube fitting within the bore of saidabutment and exerting force thereon and removable from said bore in adirection of the axis of said hub, said hydraulic control means beingremovable from, and replaceable in, said hub as a single unit.

9. A controllable pitch propeller comprising a hub, propeller bladesmounted in said hub, a sleeve slidably reciprocally mounted in said hub,means so connecting said sleeve and blades that said blades will moveabout their axes simultaneously with, and in proportion to the extentof, an axial movement of said sleeve, a cylinder carried by the frontend portion of said sleeve, and a cylinder head removably secured tosaid cylinder, in combination with. a piston making a working slidingfit in said cylinder and having a central bore, a flexible diaphragmhaving its peripheral portion clamped between said cylinder and cylinderhead and its central portion secured against said piston at all pointsabout the bore thereof, an abutment plate having -a smooth central boreconcentric with said sleeve and cylinder and rigidly mounted in saidhub, a tubular piston rod making a snug endwise sliding removable fit inthe bore of said abutment plate and exerting a thrust against the sameand having its front end portion rigidly secured to said piston andestablishing communication between the space to the rear of saidabutmentplate and the space between said diaphragm and said cylinderhead, said piston, piston rod and diaphragm being removable andreplaceable as a unit by a simple axial pull or push when the cylinderhead has been removed.

10. A controllable propeller comprising an integral one-piece nub,propeller blades mounted in said hub, a spider disposed in said hub formovement in the direction of the axis thereof, means forv preventingrotary movement of said spider relative to said hub and ior soconnecting said spider and blades that said blades will move about theiraxes simultaneously with, and in proportion to the extent or, an axialmovement of the spider, in combination with hydrauhc control meansconnected with said spider ior causing movement 01' said spider in onedirection axially of said hub, means ior limiting the extent or movementof .5810. spider in S510. direction, and releasable means for locxingsaid hydraulic control means in said hub, said control means beingoperable to ad ust said spider to dinerent positions axially of saidhub, and said hydrauhc control means being removable from andreplaceable in said hub as a single operative unit.

11. In a controllable pitch propeller comprising a hub and bladesmounted I01 pitch movement relative to said hub and to turn with saidhub, an externally screw-threaded sleeve slidably mounted in the hub ofthe propeller for reciprocation axially or the hub, an internallyscrewthreaded spider having screw-thread engagement with the externalscrew-threads of said sleeve, means connecting said spider and theblades of the propeller to cause much movement of said blades bymovement of said spider in one direction axially of the propeller hub,and releasable 14 adjustable in position axially of the sleeve byrotating the sleeve within said spider.

12. In a controllable pitch propeller comprising a hub and bladesmounted for pitch movement relative to. said hub and to turn with saidhub, an externally screw-threaded sleeve slidably mounted in the hub ofthe propeller for reciprocation axially thereof, an internallyscrewthreaded spider having screw-thread engagement with the externalscrew-threads of. said sleeve, means for preventing rotation of saidspider relative to said hub and for connecting said spider and theblades of the propeller to cause pitch movement of said blades bymovement of said spider in one axial direction, a nut engaging thethreads of said sleeve and normally turning therewith and limiting axialmovement of said spider in .said direction by engaging a relativelyfixed part carried by said hub, and releasable means for holding saidsleeve against rotation, said nut being adjustable axially of the sleeveindependently of said spider.

1-3. In a controllable pitch propeller comprising a hub and bladesmounted for pitch movement relative to said hub and to turn with saidhub, an externally screw-threaded element slidably mounted in the hub ofthe propeller for reciprocation axially thereof, an internallyscrewthreaded spider receiving and engaging the threads of said element,means for preventing spider, and said mechanism and element beingremovable from and replaceable in said hub as a unit.

MARTIN M. SENSENICH. HAROLD R. UHRICH.

nimmnucns crrnn The following references are of record inthe file ofthis patent:

um'rnn s'rs'rns Pii'mn'rs Number Name Date 157,277 Curtis Dec. 1,1874157,298 Secor Dec. 1,1874 233,398 Briggs Oct. 19, 1880 1,832,783Lorenzen Nov. 17,1981 1,967,461 Ballew July 24, 1934 2,032,255 CaldwellFeb. 25, 1936 2,083,569 Larason June 15, 1937 2,233,468 Barthel et a].Mar. 4, 1941 2,304,153 DiCesare Dec. 8,1942 2,371,187 Roby Mar. 13, 19452,392,341 Squier Jan 8, 1946 FOREIGN PATENTS Number Country Date 175,508Switzerland Feb. 28. 1935 346,844 Great Britain Apr. 1931 449,407 GreatBritain June 26, 1936 635,992 Germany Sept. 10. 1934

